The present invention relates to the general field of locking/unlocking systems for a cover of a container which forms a cooking vessel, preferably of the pressure type, as well as to control devices for displacing the jaws which assure locking.
The present invention concerns more specifically a device for controlling the opening and closing of jaws which are mounted for radial movement on the cover via drive arms, the jaws being intended to assure the locking of the cover on a container to form a cooking vessel, preferably of the pressure type.
There is already known in the art, for example as disclosed in published International Application 92/03080, a pressure cooking vessel using a locking/unlocking device composed of jaws which are mounted for radial movement on the cover. The jaws, of which there are two, are diametrically opposite one another relative to the longitudinal axis of the vessel and are adapted such that when in their closing position they tightly grip the peripheral edge of the container in order to hermetically seal the vessel. Conversely, the jaws can occupy an unlocking position permitting opening of the vessel. Control of the displacement of the jaws is assured by a control means, which is a button mounted to move axially on the cover in a central position. The control means is provided with engagement surfaces which are specially shaped to act, during displacement of the control button, on inclined surfaces fixed to the jaws in order to displace them radially. Such a control system thus transforms, in a conventional manner, an axial movement into a radial displacement movement of the jaws between a closing position and an opening position.
It can be considered that such a device represents a positive contribution to systems for locking vessels in a closed position for pressure cooking, particularly because it does not require a relatively precise positioning between the cover and the container before the control means are operated. On the other hand, such a system has been found to require a series of pieces which are movable relative to one another, and in particular radially, to assure control of disengagement of the jaws. The arrangements proposed thus far imply combinations of movements, such as translations and rotations, provoking risks of significant jamming and leading to high fabrication costs and a less than optimum operating reliability.
It is equally in order to note that the control mechanism of the above-described device, as well as the relative displacements of the various parts, requires a relatively substantial physical effort on the part of the user.
Moreover, it has been found that the jaw displacement control device disclosed in the above-cited patent offers less than optimum operating safety and ergonomics. In effect, the use of a control button, for opening and closing the jaws, disposed in a central position on the cover and which is displaced axially by pushing down in order to effect either opening or closing of the jaws, constitutes an inconvenience from the ergonomic standpoint and can present safety risks. Thus, it appears that the utilization of the same direction of movement to perform the two opposed functions of opening and closing of the jaws does not permit the user to establish, in a natural and instinctive manner, a unique association between a manual action, such as pushing, and a result, such as opening or closing. In this case, the same movement corresponds to different and opposite results. The control button can also serve conveniently as an element for gripping the vessel and can tempt the user to transport the vessel while under pressure via that gripping element and can even, because of the difficulty of memorizing a correct movement, cause the user to inadvertently manipulate the button, with the resulting danger of causing the vessel to open while under pressure.